The dielectric relaxation study for the hydrogen bonded binary system of polar liquid isopropyl alcohol in non-associated liquids-methyl benzoate and ethyl benzoate has been carried out, using the HP-LF impedance analyzer in static region, Plunger method in microwave frequency region and Abbe's refractometer in optic region, at different temperature and mole fractions. The dielectric parameters viz. static, optic permittivity, excess permittivity, Bruggeman parameter, relaxation time, excess inverse relaxation time and thermodynamic parameters have been obtained. The dielectric parameters show systematic change with temperature and concentrations. Conformational analysis of the formation of hydrogen bond in the binary mixture systems isopropyl alcohol with methyl benzoate and ethyl benzoate is supported by FT-IR. Hamiltonian quantum mechanical calculations such as AM1, PM3 and MNDO optimized converged geometry operation is performed by using Spartan Modeling software for both pure and equi molar systems and thus the FT-IR spectra are obtained and further compared with the experimental values. © 2010 Elsevier B.V. All rights reserved.